Street hockey is commonly played with either a ball or with a plastic disc-shaped object ("puck") similar in appearance to an ice hockey puck. While the size of street hockey pucks is similar to the size of regulation ice hockey pucks (which are approximately 3 inch (7.62 cm) diameter and 1 inch (2.54 cm) thick), other characteristics are necessarily different due to the varying characteristics of the playing surface upon which the two sports are played.
Whereas common ice hockey pucks are typically constructed of rubber and, when struck, may slide nicely on either of their two flat sides over ice, when such pucks are used on relatively more rough playing surfaces (such as floors, paved streets, parking lots, or other surfaces) they do not glide smoothly across such surfaces, but rather tend to stick or sporadically bounce and roll across such non-slick surfaces.
To overcome some of the problems relating to prior disc-shaped pucks travelling over non-slick surfaces, balls have been employed on occasion in street hockey games in place of disc-shaped pucks due to the ability of the balls to roll smoothly over most flat surfaces. Although balls generally travel more evenly, smoothly and controllably over relatively rough playing surfaces than do ice hockey pucks and prior street hockey pucks, the fact that the balls are spherically shaped (rather than disc-shaped) inherently changes the nature of the game when balls are used. Other problems associated with the use of balls are that they interact poorly with hockey sticks and they tend to travel at high speeds.
Plastic street hockey pucks of various designs are known. Some prior street hockey puck designs incorporate the use of ball bearings, (for example as disclosed in U.S. Pat. No. 4,793,769). Although the use of ball bearings in street hockey puck design does allow a rolling effect on the playing surface, many surfaces are not quite smooth enough to effect a desirable consistency of performance of the puck, as such prior puck designs do not provide for the dissipation of the frictional effects of these surfaces; hence the puck tends to tumble and roll in an undesirable way. The ball bearings themselves of such prior pucks are also easily scarred and soiled as to prohibit their efficient rolling motion; and the cost to manufacture street hockey pucks comprising ball bearings is typically significantly higher than the cost of manufacturing pucks without ball bearings.
Other prior street hockey pucks are generally of single component construction, typically being molded into a homogenous plastic disc. This prior design typically varies from the construction of ice hockey pucks principally in that the street hockey pucks are typically made of plastic (having a density of 0.89 to 0.93 to grams per cubic centimeter), which is significantly less dense than regulation ice hockey pucks which are made of vulcanized rubber (having a density of 1.34 to 1.46 grams per cubic centimeter). Accordingly, prior plastic pucks typically are of relatively light-weight and tend to bounce and tumble easily after being struck with a hockey stick. This prior design of street hockey puck typically renders the puck very hard for the player to "feel" while dribbling the puck (due to its very light weight, and due to its rapid loss of speed/momentum).
As a consequence of the relatively light weight of these prior street hockey pucks- (typically prior plastic street hockey pucks 3.75" (9.52 cm) diameter by 7/8" (2.22 cm) thick weigh in the range of 140 to 146 grams)- several unfavorable things occur. As will be appreciated by those skilled in the art, because the net frictional force between the puck and the playing surface and the momentum of the travelling puck are both directly proportional to the weight of the puck, the rate of deceleration resulting from friction between a puck and a playing surface is independent of the weight (or density) of the puck.
However, because the net friction force between the puck and the air (i.e. wind drag) depends only on the geometry of the puck and its speed through the air, and is therefore independent of the weight (or density) of the puck, a low weight (or low density) puck may be slowed down considerably more by air friction than would a similarly sized and similarly shaped heavier (or more dense) puck. Accordingly, due to the relatively low density of common prior plastic street hockey pucks (i.e. less than 0.94 grams per cubic centimeter), prior pucks disadvantageously lose speed more quickly as a consequence of wind drag, than do regulation ice hockey pucks (1.34 to 1.46 grams per cubic centimeter).
In addition, the combined effects of wind drag on the relatively light-weight prior plastic pucks, together with the relatively high coefficient of restitution associated with the homogeneous construction of prior molded pucks, tend to cause prior pucks to bounce and tumble across the playing surfaces in an undesirable manner, rather than slide on the flat plane of the playing surface.
All of these, above, factors associated with prior street hockey pucks tend to change the nature of the game from a fast-paced game of skill to one of luck and chance.
The most desirable performance characteristic for street hockey pucks is that they substantially simulate the performance of ice hockey pucks in ice hockey games. However, the similarity of performance between ice hockey pucks used in ice hockey games and street hockey pucks used in street hockey games is often compromised due to the relatively higher surface friction inherent in street hockey playing surfaces as compared with ice hockey playing surfaces (i.e. smooth ice). The typical range for coefficient of friction (sliding) between a regulation ice hockey puck (vulcanized rubber) and ice is 0.05 to 0.20. The typical range of coefficient of friction (sliding) between prior plastic disc-shaped street hockey pucks and cement or asphalt pavements is approximately 0.40 to 0.70 for molded plastic pucks, and 0.50 to 0.80 for molded synthetic rubber pucks.
Standard ice hockey pucks are of substantial mass (approximately 156-170 grams) and are heavy enough to be "felt" by the player while being handled with a hockey stick. A puck of reduced weight (i.e. below 150 grams) is hard to "feel" when stick handling (dribbling) the puck over the playing surface. Lightweight puck construction requires the player to watch the puck, as opposed to being able to "feel" it with the stick.
Street hockey balls are used to combat the effects of friction on semi-smooth surfaces. These hollow balls are effective in combatting frictional effects but, as discussed above, do not behave characteristically like an ice hockey puck. In many prior street hockey ball designs, the ball is constructed of a compressible synthetic rubber, or the like. The compressibility of such balls introduces undesirable performance of the balls, due to the energy loss when the stick strikes the ball.